Effects of linalool on glutamatergic system in the rat cerebral cortex

Linalool is a monoterpene compound reported to be a major component of essential oils in, various aromatic species. Several Linalool-producing species are used in traditional medical systems, includingAeolanthus suaveolens G. Dom (Labiatae) used as anticonvulsant in the Brazilian Amazon. Psychopharmacological in vivo evaluation of Linalool showed that this compound have dose-dependent marked sedative effects at the Central Nervous System, including hypnotic, anticonvulsant and hypothermic properties. The present study reports an inhibitory effect of Linalool on Glutamate binding in rat cortex. It is suggested that this neurochemical effect might be underlining Linalool psychopharmacological effects. These findings provide a rational basis for many of the traditional medical use of Linalool producing plant species.     

Effects of spinal transection on presynaptic markers for glutamatergic neurons in the rat

To evaluate the hypothesis that glutamic acid may be the neurotransmitter of descending, excitatory supraspinal pathways, the uptake and release ofl-[³H] glutamate and the levels of endogenous glutamate were measured in preparations from rat lumbar spinal cord following complete mid-thoracic transection. Following transection, the activity of the synaptosomal high-affinty glutamate uptake process was increased in both dorsal and ventral halves of lumbar cord between 1 and 14 days after transection and returned to control levels by 21 days posttransection. At 7 days, the increased activity of the uptake process forl-[³H] glutamate resulted in elevation ofV _max with no significant alteration inK _t as compared to age-matched controls. Depolarization-induced release ofl-[³H]glutamate from prelabeled slices did not differ significantly from control in the lesioned rat except at 21 days after lesion when the amount of tritium release was significantly greater in the transected preparations than in control. Amino acid analysis of the lumbar cord from control and transected rats indicated only a 10% decrease in the level of endogenous glutamate and no alterations in the concentration of GABA and glycine 7 days after lesion. These findings do not support the hypothesis that glutamate serves as a major excitatory neurotransmitter in supraspinal pathways innervating the lumbar cord of the rat.     

Differential presynaptic effects of hexachlorocyclohexane isomers on noradrenaline release in cerebral cortex.

To investigate presynaptic effects of hexachlorocyclohexane (HCH) isomers, the release of noradrenaline (NA) in brain tissue was analyzed using rat cerebral cortical slices preloaded with [3H]-NA. gamma-HCH (lindane) 50 microM significantly enhanced the [3H]-NA release evoked by 15-25 mM K+. alpha- and beta-HCH (50 microM) did not produce any significant effect on K(+)-evoked [3H]-NA release. delta-HCH (50 microM) induced a significant decrease of the 25 mM K(+)-evoked release of [3H]-NA. The effect of the gamma- and delta-HCH isomers on the presynaptic action of the alpha 2-agonist clonidine and the alpha 2-antagonist yohimbine was also studied. The presynaptic inhibitory effect of clonidine and the stimulatory effect of yohimbine on [3H]-NA release was attenuated by lindane and delta-HCH, respectively. These results are consistent with a presynaptic action of the HCH isomers on noradrenergic release processes.     

Independent development of presynaptic specializations in olfactory cortex of the fetal rat

Summary Electron microscopy was used to study synaptogenesis in prepyriform cortex of fetal rat pups during early stages of synapse formation. Of special interest is the frequent occurrence of unapposed, developing synaptic specializations in axon and growth cone profiles. The location and morphology of the unapposed specializations suggests that thay are presynaptic in nature. These presumably immature presynaptic specializations are found in the lateral olfactory tract and subjacent cortex. Intermediate forms between uncontacted presynaptic specializations and definitive synapses suggest a synaptogenic sequence in which initial development of an immature presynaptic specialization begins without apposition of a postsynaptic element at that location. This implies that initiation of presynaptic development is not dependent upon postsynaptic contact and also raises the question of whether synaptic contacts could be established via presynaptic induction of postsynaptic formation.Dr. Westrum is an Affiliate of the CDMRC at the University of Washington. The research was supported in part by NIH Grants NS09678, NS17111 (NINCDS), and DE04942 (NIDR), DHHS     

Effects of antidepressive agents on tolerance of hypoxia and physical exercise]

In experiments on mice and rats we studied the influence of antidepressants on hypoxic and physical tolerance. The antidepressants pyrazidol, azaphen, imipramine and moclobemide as well as the nootropic drug piracetam prolonged the life of animals in conditions of hypoxic and hemic hypoxia and increased the survival rate of rats in circulatory hypoxia. In experiments on mice antidepressants increased also the time of swimming.     

Effects of environment on morphology of rat cerebral cortex and hippocampus.

Cortical depth differences were found between male rats exposed to enriched or impoverished environmental conditions for successively shorter times, i.e., for 15 days (from 25 to 40 days of age), for seven days (25 to 32 days of age), and for four days (26 to 30 or 60 to 64 days of age). If the experiments began at weaning (at 25 days of age), the cortical depth changes were caused primarily by impoverishment. If the animals were young adults (60 days of age), upon entering their respective conditions, the cortical changes were induced by enrichment. No cortical depth differences were found between enriched and impoverished rats after one day of differential experience, from 60 to 61 days of age. In every age group and for every duration, except for the one day group, the dorsal-medial segment of the occipital cortex responded to the environmental conditions. No significant hippocampal depth differences were noted between enriched and impoverished animals.     

Effects of alpha-methyl-p-tyrosine on monoamines and catecholamine receptors in rat cerebral cortex and neostriatum

The effects of inhibiting the synthesis of catecholamines using -methyl-p-tyrosine (-MPT) were investigated in four cortical regions (cingulate, somatosensory, visual and entorhinal-piriform) as well as in the neostriatum (caudate-putamen). After acute (48 hours) treatments with -MPT the endogenous NA levels were significantly reduced in all regions examined. The DA contents were also decreased in regions known to posses a dense dopaminergic innervation (neostriatum, cingulate and entorhinal-piriform cortices) but not in the somatosensory and visual areas, where DA is normally present in small amounts. Serotonin and 5-HIAA levels were either unaffected or increased. After such catecholamine synthesis inhibitions, there were no changes in the binding parameters (B _max andK _d) of [³H]prazosin (₁-receptors), [³H]idazoxan (₁-receptors), [³H]dihydroalprenolol (total receptors) in the cerebral cortex nor in [³H]SCH23390 sites (dopamine D₁ receptors) in both cerebral cortex and neostriatum. The results indicate that acute catecholamine depletions but with conservation of the fibers do not produce receptor modifications.     

高原低氧对大鼠大脑皮质生长休止蛋白7表达的影响

目的 探讨高原低氧对大鼠大脑皮质生长休止蛋白7(Gas7)表达的影响.方法 36只大鼠随机分为正常对照组和模拟高原低氧组,模拟高原低氧组大鼠进行6周缺氧,复制慢性高原低氧动物模型.实验结束后,所有动物采用免疫组织化学和免疫印迹技术检测大鼠大脑皮质中Gas7的表达.结果 与对照组相比,Gas7在模拟高原低氧组大鼠大脑皮质的表达明显增强.结论 Gas7可能参与了高原低氧对大鼠大脑皮质神经元结构和功能的影响.     

Effects of astroglia on the development of cultured neurons from embryonic rat cerebral cortex.

1. Previous studies from our laboratory demonstrated that subcultured astroglia enhance neurite outgrowth and survival of cultured neurons from embryonic rat cerebral cortex, but suppress proliferation of neuroblasts. 2. In the present study, the mechanisms of these three effects were further investigated. 3. Dissociated neurons were seeded on poly-L-lysine-coated coverslips which were plated on subcultured astroglia, and the survival, proliferation and neurite outgrowth of the neurons were investigated. Under these conditions, survival and antimitotic effects were also observed, while neurite extension was not stimulated. 4. The results clearly indicate that neuronal survival and proliferation are regulated by soluble factors produced by astroglia. 5. We also postulated that the neurite-promoting effect of astroglia is mediated by cell-cell contact. 6. This idea was confirmed by the finding that neurite extension was enhanced when the neurons were cultured directly on heat-treated astroglia. 7. The neurite-promoting effect was found to be specific to astroglia. 8. We preliminarily characterized the astroglial surface neurite-promoting factors (ASNPFs). 9. The relationship of laminin to ASNPFs was examined by using antibody to laminin. Laminin antibody did not inhibit the ASNPF activity. 10. The effect of digestion of heat-treated astroglia with enzymes (sialidase and endo-beta-galactosidase) on the ASNPF activity was also examined. 11. These enzyme treatments did not inhibit the ASNPF activity. 12. These results suggest that enhancement of the neurite-promoting activity is not associated with the sugar moiety of ASNPFs.     

Acetylcholinesterase in neurons of the rat cerebral cortex.

AChE-containing neurons have been demonstrated by electron-microscopical histochemistry in the neocortex of the rat. These cells are mainly located in layer VI. AChE activity is seen in the cisternae of the RER, in subsurface cisternae and in the dendritic membranes.